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SELECT * 
FROM Item 
INNER JOIN 

(
SELECT item_id, MAX(bid_id) 
FROM Bid 
GROUP BY item_id 
)

AS maxbids 

ON (Item.item_id = maxbids.item_id) 

INNER JOIN Category 
ON (Item.category_id = Category.category_id) 

INNER JOIN Bid 
ON (maxbids.bid_id = Bid.bid_id)